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Joint Entrance Examination
Mathematics
Probability
Question 240
Question 240 of 417
Easy
MCQ
An unbiased coin tossed 8 times. Find the probability of at least one head and at least one tail.
A
255
/
256
255/256
255/256
B
127
/
128
127/128
127/128
C
63
/
64
63/64
63/64
D
1
/
2
1/2
1/2
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Official solution
\[P = 1-\left[\left(\frac12\right)^8+\left(\frac12\right)^8\right] = 1-\frac{1}{128}=\frac{127}{128}\]
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